In April 2024, the federal government issued a set of regulations including defined maximum contaminant levels for five per- and polyfluoroalkyl substances and an equation called the Hazard Index for a combination of four PFAS. After the administration transitioned to new leadership, the regulations were scaled back to only maintain the National Primary Drinking Water Regulations for perfluorooctanoic acid and perfluorooctane sulfonic acid at 4 parts per trillion. This change also extended the timeline of required compliance an additional two years before action can be taken by the federal government against a municipality for failure to comply. Municipalities must still complete testing
